| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1990: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1989: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1988: ¥900,000 (Direct Cost: ¥900,000)
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| Research Abstract |
Roles of the medullary raphe nuclei in regulating female and male sexual behaviors were investigated in rats.
In ovariectomized rats, the raphe obscurus nucleus (ROBN) or the raphe magnus nucleus (RMGN) was destroyed by radio frequency lesion generator. Four-5 weeks after operations, all females were implanted with a Silastic tubing containing estradiol (E_2). Sexual behavioral tests were started 2 days after E_<> implantations and carried out daily for 5 days. ROBN lesion-females showed high levels of lordosis quotient (LQ) in the first test, when compared with those of non-brain surgery and sham operated females. The mean LQ of RMGN lesion group was comparable to those of control groups. In addition, incidence of ear-wiggling in ROBN lesion group was higher than those in other groups. These results suggest that the raphe obscurus nucleus play an inhibitory role in regulating female rat sexual behaviors.
In castrated male rats, ROBN or RMGN was destroyed. Four-5 weeks after operation, all males were implanted Silastic tubings containing testosterone. Sexual behavior tests were started 1 week after testosterone administration and 3 tests were carried out 1 week intervals. In ROBN lesion group, frequencies of mounting, intromission and ejaculation were lower than those in RMBN lesion, non-brain surgery and sham operated groups. These results suggest that in contrast to the female case, the raphe obscurus nucleus play a facilitatory role in regulating male rat sexual behaviors. Furthermore, after treatment with p-chlorophenylalanine (PCPA, an inhibitor for serotonin synthesis), ROBN lesion-males showed higher frequencies of sexual behaviors than those in non-PCPA treated ROBN lesion males, but the frequencies were lower than those in PCPA treated non-brain surgery control males. Thus, PCPA may act on serotonergic neurons other than those in the ROBN and facilitate male sexual behaviors in male rats.
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